1. Field of the Invention
The present invention relates to a hybrid compressor having two compression mechanisms driven by drive sources different from each other.
2. Description of Related Art
A hybrid compressor capable of being driven by an internal combustion engine of a vehicle or an electric motor, or both, is described in Japanese Utility Model (Laid-Open) No. 6-87678 and JP-A-2000-130323. Such hybrid compressors include a clutch for the engagement of a single compression mechanism to an internal combustion engine of a vehicle or an electric motor incorporated into the compressor, or both, and for the disengagement of such a single compression mechanism from such an engine or motor or both.
Nevertheless, in hybrid compressors, such as those described in Japanese Utility Model (Laid-Open) No. 6-87678 and JP-A-2000-130323, it is difficult to adapt the single compression mechanism to two drive sources, such as an engine and an electric motor, which differ from each other in output characteristics. In particular, because the engine and the electric motor, which differ from each other in output characteristics, are switched selectively as the drive source, it is difficult or impossible to operate each drive source at a maximum or optimal efficiency. Further, a pulsation in the output of such compressors also may occur when the drive sources are switched. In order to suppress such pulsation, it may be necessary to increase the capacity of the discharge chamber and of the suction chamber. However, because a discharge chamber and a suction chamber are formed within a compressor housing, if the capacities of the discharge chamber and the suction chamber are increased, the length of the housing and the size of the compressor also increase.